/*
** $Id: lundump.c,v 2.7.1.4 2008/04/04 19:51:41 roberto Exp $
** load precompiled Lua chunks
** See Copyright Notice in lua.h
*/

#include <string.h>

#define lundump_c
#define LUA_CORE

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstring.h"
#include "lundump.h"
#include "lzio.h"

typedef struct
{
    lua_State *L;
    ZIO *Z;
    Mbuffer *b;
    const char *name;
    int swap;
    int numsize;
    int toflt;
    size_t total;
} LoadState;

#ifdef LUAC_TRUST_BINARIES
#define IF(c,s)
#define error(S,s)
#else
#define IF(c,s)     if (c) error(S,s)

static void error(LoadState *S, const char *why)
{
    luaO_pushfstring(S->L, "%s: %s in precompiled chunk", S->name, why);
    luaD_throw(S->L, LUA_ERRSYNTAX);
}
#endif

#define LoadByte(S)     (lu_byte)LoadChar(S)
#define LoadVar(S,x)        LoadMem(S,&x,1,sizeof(x))
#define LoadVector(S,b,n,size)  LoadMem(S,b,n,size)

static void LoadBlock(LoadState *S, void *b, size_t size)
{
    size_t r = luaZ_read(S->Z, b, size);
    IF(r != 0, "unexpected end");
    S->total += size;
}

static void LoadMem(LoadState *S, void *b, int n, size_t size)
{
    LoadBlock(S, b, n * size);
    if (S->swap && b)
    {
        char *p = (char *) b;
        char c;
        switch (size)
        {
        case 1:
            break;
        case 2:
            while (n--)
            {
                c = p[0];
                p[0] = p[1];
                p[1] = c;
                p += 2;
            }
            break;
        case 4:
            while (n--)
            {
                c = p[0];
                p[0] = p[3];
                p[3] = c;
                c = p[1];
                p[1] = p[2];
                p[2] = c;
                p += 4;
            }
            break;
        case 8:
            while (n--)
            {
                c = p[0];
                p[0] = p[7];
                p[7] = c;
                c = p[1];
                p[1] = p[6];
                p[6] = c;
                c = p[2];
                p[2] = p[5];
                p[5] = c;
                c = p[3];
                p[3] = p[4];
                p[4] = c;
                p += 8;
            }
            break;
        default:
            IF(1, "bad size");
            break;
        }
    }
}

static int LoadChar(LoadState *S)
{
    char x;
    LoadVar(S, x);
    return x;
}

static void Align4(LoadState *S)
{
    while (S->total & 3)
        LoadChar(S);
}

static int LoadInt(LoadState *S)
{
    int x;
    LoadVar(S, x);
    IF(x < 0, "bad integer");
    return x;
}

static lua_Number LoadNumber(LoadState *S)
{
    lua_Number x;
    if (S->toflt)
    {
        switch (S->numsize)
        {
        case 1:
        {
            int8_t y;
            LoadVar(S, y);
            x = (lua_Number)y;
        }
        break;
        case 2:
        {
            int16_t y;
            LoadVar(S, y);
            x = (lua_Number)y;
        }
        break;
        case 4:
        {
            int32_t y;
            LoadVar(S, y);
            x = (lua_Number)y;
        }
        break;
        case 8:
        {
            int64_t y;
            LoadVar(S, y);
            x = (lua_Number)y;
        }
        break;
        default:
            lua_assert(0);
        }
    }
    else
    {
        LoadVar(S, x); /* should probably handle more cases for float here... */
    }
    return x;
}

static TString *LoadString(LoadState *S)
{
    int32_t size;
    LoadVar(S, size);
    if (size == 0)
        return NULL;
    else
    {
        char *s;
        if (!luaZ_direct_mode(S->Z))
        {
            s = luaZ_openspace(S->L, S->b, size);
            LoadBlock(S, s, size);
            return luaS_newlstr(S->L, s, size - 1); /* remove trailing zero */
        }
        else
        {
            s = (char *)luaZ_get_crt_address(S->Z);
            LoadBlock(S, NULL, size);
            return luaS_newrolstr(S->L, s, size - 1);
        }
    }
}

static void LoadCode(LoadState *S, Proto *f)
{
    int n = LoadInt(S);
    Align4(S);
    if (!luaZ_direct_mode(S->Z))
    {
        f->code = luaM_newvector(S->L, n, Instruction);
        LoadVector(S, f->code, n, sizeof(Instruction));
    }
    else
    {
        f->code = (Instruction *)luaZ_get_crt_address(S->Z);
        LoadVector(S, NULL, n, sizeof(Instruction));
    }
    f->sizecode = n;
}

static Proto *LoadFunction(LoadState *S, TString *p);

static void LoadConstants(LoadState *S, Proto *f)
{
    int i, n;
    n = LoadInt(S);
    f->k = luaM_newvector(S->L, n, TValue);
    f->sizek = n;
    for (i = 0; i < n; i++) setnilvalue(&f->k[i]);
    for (i = 0; i < n; i++)
    {
        TValue *o = &f->k[i];
        int t = LoadChar(S);
        switch (t)
        {
        case LUA_TNIL:
            setnilvalue(o);
            break;
        case LUA_TBOOLEAN:
            setbvalue(o, LoadChar(S) != 0);
            break;
        case LUA_TNUMBER:
            setnvalue(o, LoadNumber(S));
            break;
        case LUA_TSTRING:
            setsvalue2n(S->L, o, LoadString(S));
            break;
        default:
            error(S, "bad constant");
            break;
        }
    }
    n = LoadInt(S);
    f->p = luaM_newvector(S->L, n, Proto *);
    f->sizep = n;
    for (i = 0; i < n; i++) f->p[i] = NULL;
    for (i = 0; i < n; i++) f->p[i] = LoadFunction(S, f->source);
}

static void LoadDebug(LoadState *S, Proto *f)
{
    int i, n;
    n = LoadInt(S);
    Align4(S);
    if (!luaZ_direct_mode(S->Z))
    {
        f->lineinfo = luaM_newvector(S->L, n, int);
        LoadVector(S, f->lineinfo, n, sizeof(int));
    }
    else
    {
        f->lineinfo = (int *)luaZ_get_crt_address(S->Z);
        LoadVector(S, NULL, n, sizeof(int));
    }
    f->sizelineinfo = n;
    n = LoadInt(S);
    f->locvars = luaM_newvector(S->L, n, LocVar);
    f->sizelocvars = n;
    for (i = 0; i < n; i++) f->locvars[i].varname = NULL;
    for (i = 0; i < n; i++)
    {
        f->locvars[i].varname = LoadString(S);
        f->locvars[i].startpc = LoadInt(S);
        f->locvars[i].endpc = LoadInt(S);
    }
    n = LoadInt(S);
    f->upvalues = luaM_newvector(S->L, n, TString *);
    f->sizeupvalues = n;
    for (i = 0; i < n; i++) f->upvalues[i] = NULL;
    for (i = 0; i < n; i++) f->upvalues[i] = LoadString(S);
}

static Proto *LoadFunction(LoadState *S, TString *p)
{
    Proto *f;
    if (++S->L->nCcalls > LUAI_MAXCCALLS) error(S, "code too deep");
    f = luaF_newproto(S->L);
    if (luaZ_direct_mode(S->Z)) proto_readonly(f);
    setptvalue2s(S->L, S->L->top, f);
    incr_top(S->L);
    f->source = LoadString(S);
    if (f->source == NULL) f->source = p;
    f->linedefined = LoadInt(S);
    f->lastlinedefined = LoadInt(S);
    f->nups = LoadByte(S);
    f->numparams = LoadByte(S);
    f->is_vararg = LoadByte(S);
    f->maxstacksize = LoadByte(S);
    LoadCode(S, f);
    LoadConstants(S, f);
    LoadDebug(S, f);
    IF(!luaG_checkcode(f), "bad code");
    S->L->top--;
    S->L->nCcalls--;
    return f;
}

static void LoadHeader(LoadState *S)
{
    char h[LUAC_HEADERSIZE];
    char s[LUAC_HEADERSIZE];
    int intck = (((lua_Number)0.5) == 0); /* 0=float, 1=int */
    luaU_header(h);
    LoadBlock(S, s, LUAC_HEADERSIZE);
    S->swap = (s[6] != h[6]);
    s[6] = h[6]; /* Check if byte-swapping is needed  */
    S->numsize = h[10] = s[10]; /* length of lua_Number */
    S->toflt = (s[11] > intck); /* check if conversion from int lua_Number to flt is needed */
    if (S->toflt) s[11] = h[11];
    IF(memcmp(h, s, LUAC_HEADERSIZE) != 0, "bad header");
}

/*
** load precompiled chunk
*/
Proto *luaU_undump(lua_State *L, ZIO *Z, Mbuffer *buff, const char *name)
{
    LoadState S;
    if (*name == '@' || *name == '=')
        S.name = name + 1;
    else if (*name == LUA_SIGNATURE[0])
        S.name = "binary string";
    else
        S.name = name;
    S.L = L;
    S.Z = Z;
    S.b = buff;
    LoadHeader(&S);
    S.total = 0;
    return LoadFunction(&S, luaS_newliteral(L, "=?"));
}

/*
* make header
*/
void luaU_header(char *h)
{
    int x = 1;
    memcpy(h, LUA_SIGNATURE, sizeof(LUA_SIGNATURE) - 1);
    h += sizeof(LUA_SIGNATURE) - 1;
    *h++ = (char)LUAC_VERSION;
    *h++ = (char)LUAC_FORMAT;
    *h++ = (char) * (char *)&x;        /* endianness */
    *h++ = (char)sizeof(int);
    *h++ = (char)sizeof(int32_t);
    *h++ = (char)sizeof(Instruction);
    *h++ = (char)sizeof(lua_Number);
    *h++ = (char)(((lua_Number)0.5) == 0); /* is lua_Number integral? */
}
